In an intelligent transport system, there is one kind of application, namely, an emergency alert, including a front accident alert, a front road passage alert, and so on; and such kind of application requires an end-to-end delay at one hundred millisecond level, so as to enable more vehicles to avoid a danger, improve travel safety, and reduce or avoid loss of life and property.
A current technology mainly uses short-distance communications, such as DSRC (Dedicated Short Range Communications), to solve the foregoing problem. Emergency alert notification is implemented through communication and forwarding between vehicles; however, the method requires that an extra short-range communication module is added on all vehicles; and therefore, communication cannot be ensured and a requirement is imposed on a communication distance, or emergency alert notification is implemented through communication and forwarding between a vehicle and a roadside device; however, in order to ensure a short delay of an emergency alert at each point, a great number of roadside devices need to be deployed, thereby resulting in a high cost.